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A chemical analysis of seven red giants of the Galactic cluster NGC 4349
Pereira, C. B.; Holanda, N.; Ramos, André A. +2 more
In this study, we undertake a comprehensive investigation of seven red giant stars of NGC 4349 (#005, #009, #079, #127, #168, #174, and #203) and one non-member star (#053). Accurate abundances of 19 chemical species and 12C/13C isotopic ratio are determined using high-signal-to-noise FEROS spectra and standard spectroscopic …
Revealing the dust grain polarization properties as a function of extinction and distance towards NGC 1893
Jose, Jessy; Wang, Jia-Wei; Lai, Shih-Ping +5 more
Dust polarization observations at optical wavelengths help us to understand the dust grain properties and trace the plane-of-the-sky component of the magnetic field. In this study, we make use of the I-band polarization data acquired from AIMPOL along with the distances (d) and extinction (AV) data to study the variation of polarization…
The pre-He white dwarfs in eclipsing binaries - III. WASP 1625-04
Hong, Kyeongsoo; Lee, Jae Woo; Park, Jang-Ho
1SWASP J162545.15-043027.9 (WASP 1625-04) has been announced as one of EL CVn candidates showing total primary eclipses and ellipsoidal variations. This paper presents the absolute properties of the binary star, based on our high-resolution spectroscopy conducted from 2015 through 2020. From the spectral analysis, the radial velocities (RVs) for b…
A speckle-imaging search for close and very faint companions to the nearest and brightest Wolf-Rayet stars
Moffat, Anthony F. J.; Howell, Steve B.; Shara, Michael M. +4 more
Gravitationally bound companions to stars enable determinations of their masses, and offer clues to their formation, evolution, and dynamical histories. So motivated, we have carried out a speckle imaging survey of eight of the nearest and brightest Wolf-Rayet (WR) stars to directly measure the frequency of their resolvable companions, and to sear…
New globular cluster candidates in the M81 group
Bell, Eric F.; Monachesi, Antonela; Bailin, Jeremy +7 more
The study of outer halo globular cluster (GC) populations can give insight into galaxy merging, GC accretion, and the origin of GCs. We use archival Subaru Hyper Suprime-Cam (HSC) data in concert with space-based GALEX, IRAC, and Gaia EDR3 data to select candidate GCs in the outer halo of the M81 group for confirmation and future study. We use a s…
Lessons from the Magellanic System and its modeling
Hammer, Francois; Wang, Jianling; Yang, Yanbin
The prominent Magellanic Stream that dominates the H I sky provides a tantalizing number of observations that potentially constrains the Magellanic Clouds and the Milky Way (MW) outskirts. Here we show that the 'ram-pressure plus collision' model naturally explain these properties, and is able to predict some of the most recent observations made a…
Measurement of redshift-space two- and three-point correlation of Lyα absorbers at 1.7 < z < 3.5: implications on evolution of the physical properties of IGM
Srianand, Raghunathan; Gaikwad, Prakash; Maitra, Soumak
We present redshift-space two-point (ξ), three-point (ζ), and reduced three-point (Q) correlation of Lyα absorbers (Voigt profile components having H I column density, NH I > 1013.5 cm-2) over three redshift bins spanning 1.7 < z < 3.5 using high-resolution spectra of 292 quasars. We detect posi…
A machine learning approach to photometric metallicities of giant stars
Sanders, Jason L.; Fallows, Connor P.
Despite the advances provided by large-scale photometric surveys, stellar features - such as metallicity - generally remain limited to spectroscopic observations often of bright, nearby low-extinction stars. To rectify this, we present a neural network approach for estimating the metallicities and distances of red giant stars with 8-band photometr…
No globular cluster progenitors in Milky Way satellite galaxies
Bovy, Jo; Boldrini, Pierre
In order to find the possible progenitors of Milky Way (MW) globular clusters, we perform orbit integrations to track the orbits of 170 Galactic globular clusters and the 11 classical MW satellite galaxies backwards in time for 11 Gyr in an MW-plus-satellites potential including the response of the MW to the infall of the Large Magellanic Cloud an…
The escape of globular clusters from the satellite dwarf galaxies of the Milky Way
Haghi, Hosein; Zonoozi, Akram Hasani; Khalaj, Pouria +2 more
Using numerical simulations, we have studied the escape of globular clusters (GCs) from the satellite dwarf spheroidal galaxies (dSphs) of the Milky Way (MW). We start by following the orbits of a large sample of GCs around dSphs in the presence of the MW potential field. We then obtain the fraction of GCs leaving their host dSphs within a Hubble …